Apparatus for separating stacked printed products

ABSTRACT

The invention pertains to an apparatus for destacking printed products such as books, brochures or book blocks for further processing, with said apparatus comprising a separating belt that takes hold of the respective product to be separated, a retaining device for preventing the residual stack from being transported further and a feed belt that is arranged upstream of the separating belt and feeds additional stacks to the separating area, wherein the retaining device comprises a movable element that is in contact with the stack and acts upon the residual stack with a force that feeds this residual stack onto the separating belt.

BACKGROUND

The present invention pertains to an apparatus for separating printed products such as, for example, books, brochures or book blocks from a stack.

Destacking apparatuses are used for separating stacked products and for feeding the separated products to a processing machine.

DE 198 11 635 A1 discloses a generic destacking apparatus that has a constant height with respect to infeed and delivery and features an endless separating belt with a non-slip surface, which is driven by a frequency-controlled drive and to which the book block stacks are successively fed, lateral boundaries for the book block stacks and a height-adjustable retaining element that forms a passage for the respective book block to be separated. The retaining element can be positioned obliquely in the conveying direction, wherein the cited publication claims that this relieves the pressure on the book block to be separated and therefore is advantageous with respect to the functional reliability during the separation process.

A support plate is positioned in the infeed of the separating belt and serves for supporting the rear edge of the second book block from the bottom relative to the separating belt while the bottom book block is pulled away. For this purpose, the aforementioned retaining element can be positioned relative to the separating belt in accordance with the format length of the book block. An intermittently driven feed belt is assigned to the separating belt in order to feed a following stack into the separating position of the separating belt up to the retaining element.

The destacking apparatus known from DE 198 11 635 A1 makes it possible to quickly and easily destack book block stacks. When destacking thick book blocks with a small format, however, it may occur that the residual stack lying on top of the bottom book block falls over backward when the bottom book block is pulled out of a tall stack.

DE 10 2005 062 198 A1 discloses an enhancement of such a destacking apparatus, in which this disadvantage is eliminated, wherein a support element is provided at a defined distance behind the stack and can be moved away for the infeed of the following stack.

In both apparatuses, the residual stack respectively slides along the retaining element until it reaches the transport plane as a result of each separating process. During the separation of unbound, temporarily glued or sewn blocks, this frequently causes the printed products to fan out and consequently results in a faulty separation thereof. Above all, pages are damaged or lost. This effect is particularly pronounced if the printed products are aligned in such a way that an unbound surface such as, for example, the fore edge cut respectively points in the transport direction.

SUMMARY

The present invention is based on the objective of realizing an apparatus for separating printed products, featuring a simple construction while eliminating the above-described disadvantages.

This objective is accomplished with a first transport device, which takes hold of and effectively transports the printed product to be separated from the stack, and a retaining device that is spaced apart from the first transport device in such a way that a passage for the respective product to be separated is created between the first transport device and the retaining device. The retaining device is arranged such that its height relative to the first transport device can be adjusted and the passage thereby can be adapted to the thickness of the printed products to be separated. In this way, the respective printed product to be separated is taken hold of by the first transport device and pulled out underneath the residual stack while the transport of the residual stack is prevented by the retaining element.

The retaining device comprises a movable element that comes in contact with the stack in such a way that it exerts a force, which is directed toward the first transport device and essentially perpendicular to the transport direction, upon the stack and thereby promotes the feed of the residual stack onto the first transport device. It is important that the printed product to be separated next is fed along the retaining device such that the force exerted by the contact element can flow through the stack, at least acting upon the printed product to be separated next. In this way, the printed product to be separated next is reliably fed into the separating plane of the first transport device and prevented from fanning out during this process. Furthermore, it is no longer necessary to position the retaining device obliquely in the transport direction such that the design as well as the handling during the operation can be simplified, for example, because the adaptation of the oblique position to the product thickness is eliminated.

The retaining device is preferably arranged in such a way that it can be positioned essentially parallel to the plane defined by the first transport device. The retaining device therefore can be respectively positioned centrally referred to the center of gravity of the stack such that a rotation of the stack about the retaining device is prevented, namely even if the width of the stack considerably exceeds the width of the retaining device. This also allows a very slim design of the retaining device and therefore very good access to the separating area.

The contact surface of the contact element, which generates the force for feeding the stack, preferably is essentially planar such that shifts within the residual stack, as well as damages to the product edges, are prevented.

In a preferred design, the contact element transmitting the downward feeding force is connected to and driven by a controllable drive such that the motion of the contact element can be easily adapted to the desired separating capacity and product parameters. This also makes it possible to purposefully interrupt the motion, for example if gaps in the product cycle occur, and to thereby gently process the printed products.

In a first preferred embodiment, the contact element is incorporated with the retaining device and comprises an endless revolving belt, wherein the run of the belt, which faces and is at least partially in contact with the front (leading) face of the stack, is driven toward the first transport device along the stack height. In this way, the belt fulfills the retaining function in the direction of the first transport device, as well as the function of feeding the residual stack onto the first transport device, such that a simple and compact design of the retaining device can be realized. In this case, the deflection area of the belt facing the first transport device defines the passage for the separation such that the feed directly up to this passage is ensured and the functional reliability of the apparatus is additionally improved.

In a second preferred embodiment, the contact element effecting the feed is realized in the form of an oscillating conveyor such that a very robust and low-maintenance construction can be realized. In this case, the drive and the mounting of the contact surface effecting the feed of the stack are designed in such a way that said contact surface essentially carries out an oscillation in a plane that is defined by the conveying direction of the first transport device and the normal to the transport plane formed by the first transport device, wherein the orientation of the oscillation is inclined relative to the feed direction of the residual stack. The arrangement of the contact surface of the oscillating conveyor acting upon the stack corresponds to that of the above-described belt.

Both embodiments preferably comprise an adjustable separating element that is arranged between the contact element effecting the feed and the stack in such a way that it shields a variable area of the contact element from the stack and thereby allows a simple adaptation of the dimension of the contact area to the printed products and the separating capacity independently of the adjusted passage. The separating element of the retaining device includes a retention plate that acts on the front face of the stack to hold back a portion of the printed products above the bottom printed product and the at least one contact element has a contact surface entirely above the first transport device and acting at the front face on at least the bottom printed product. The contact element is adjustable with respect to its distance from the first transport device, and the retention plate is adjustable relative to the contact element with respect to its distance from the first transport device.

A third preferred embodiment comprises a feeding contact element in the form of a pressing element that is arranged above the first transport device, wherein said pressing element is placed on top of the stack and feeds the stack as a whole. This allows a particularly simple and functionally reliable construction of the separating device. The drive is simply realized in the form of a pneumatic cylinder such that the feeding force can be maintained constant and, in particular, is not dependent on the height of the residual stack.

A second transport device is provided for feeding following stacks onto the first transport device. It is particularly simple and cost-efficient if both transport devices are realized in the form of conveyor belts.

BRIEF DESCRIPTION OF THE DRAWING

An exemplary embodiment of the inventive apparatus is described in greater detail below with reference to the drawing, in which:

FIG. 1 shows a simplified perspective view of an apparatus for separating stacked printed products, and

FIG. 2 shows a simplified and partially sectioned perspective view of a retaining device.

DETAILED DESCRIPTION

FIG. 1 shows a general view of an inventive apparatus for separating stacked printed products with a separating belt 3, which is driven by a controllable drive 4 that communicates with a control C of the apparatus, a feed belt 5, which is driven by another controllable drive 6 that communicates with the control C of the apparatus, and a frame 23 that accommodates the retaining device 9. Both conveyor belts 3 and 5 are essentially arranged horizontally and in alignment with one another, particularly without an offset in height, and have the same transport direction v. The apparatus comprises light barriers 7, 8 that detect product stacks at different positions on the conveyor belts 3 and 5 and are also connected to the control C in order to control the feed motion of the belts.

The passage 24 for the respective product to be separated is defined by the distance of the retaining device 9 above the separating belt 3 and can be adjusted by means of a height adjusting mechanism 18 that connects the retaining device 9 to the frame 23. In order to achieve a continuous and precise adaptation of the passage 24, the height adjusting mechanism 18 comprises a spindle 19 that allows a very precise adjustment, particularly to thin printed products.

The position of the retaining device 9 can be continuously adjusted, as well as fixed with the aid of clamping means 21, in a plane defined by the conveyor belts 3 and 5 with the aid of linear guides 20 and 22 that are arranged perpendicular to one another in a plane extending parallel to the separating belt 3. In this way, the retaining device 9 can be positioned centrally referred to the stack such that a rotation of the stack about the vertical axis is prevented. The adjustment parallel to the transport direction v allows an adaptation to the stack dimension in this direction. In contrast to the height adjusting mechanism 18, a simple manual displacement is sufficiently precise in this case.

FIG. 2 shows the retaining device 9, wherein areas of the supporting frame are illustrated in a sectioned fashion in order to elucidate the construction. An endless revolving belt 10 is arranged in the frame. This belt is driven by a motor 15 that communicates with the control C of the apparatus via a drive pulley 11 and wrapped around a return pulley 25, as well as a tension pulley 12. The run facing the stack moves perpendicularly toward the separating belt 3 in the feed direction d and is guided and supported relative to the stack by a cleat 13.

The belt 10 runs around an edge 14 of the cleat 13 in the region of the closest approach of the belt 10 to the separating belt 3 and therefore in the passage 24. The thusly achieved sharp deflection of the belt 10 allows a reliable separation of printed products that have a significantly smaller thickness than the radius of the deflection pulley.

In order to adapt the effective area of the belt 10 to the thickness of the printed products to be separated, a plate is provided as a shield 16 of the belt 10 relative to the stack, wherein said plate can be displaced in the feed direction d in oblong holes and fixed with clamping means 17. In this way, the belt 10 only acts upon a certain number of lower printed products of the stack whereas products of the residual stack located in the region of the shield 16 are not taken hold of. A gentle separation of the products consequently can also be realized with a continuously driven belt 10 and therefore a simple actuation of the drive 15. 

1. An apparatus for sequentially separating individual printed products that are stacked in a height direction between top and bottom printed products, comprising: a first transport device that acts upon the respective sequential bottom printed product along a first feed direction (v) extending perpendicular to the stack height, a second transport device that is arranged upstream of the first transport device and feeds stacks thereto along said first fed direction, and a height-adjustable retaining device that holds back printed products above the bottom printed product from transport in the first feed direction and forms a passage with the first transport device for the respective bottom printed product to be separated from the stack as transported along the first feed direction by the first transport device, wherein the retaining device includes at least one movable contact element which contacts a surface of the stack with a force acting in a direction (d) toward the first transport device and perpendicular to the first feed direction (v).
 2. The apparatus according to claim 1, wherein the first transport device moves along an imaginary transport plane and the retaining device is repositionable relative to the first transport device in two directions that lie on another imaginary plane that is parallel to the transport plane.
 3. The apparatus according to claim 1, wherein the stack defines a planar front face and the at least one contact element of the retaining device has a planar contact surface acting upon said front face to hold back printed products above the bottom printed product.
 4. The apparatus according to claim 1, wherein the at least one contact element of the retaining device is connected to and driven by a controllable drive.
 5. The apparatus according to claim 1, wherein the stack defines a front face and at least one contact element of the retaining device comprises an endless revolving belt, arranged at the front face of the stack to be separated, for taking hold of at least an area of the front face.
 6. The apparatus according to claim 1, wherein the at least one contact element comprises an oscillating conveyor arranged at the front face of the stack to be separated for taking hold of at least an area of the front face of the stack to be separated.
 7. The apparatus according to claim 1, including a separating element that is arranged between the contact element of the retaining device and the stack of printed products to be separated and can be adjusted with respect to its distance from the passage between the retaining element and the first transport device.
 8. The apparatus according to claim 1, wherein the at least one contact element is formed by a pressing element arranged above the first transport device.
 9. The apparatus according to claim 1, wherein the first transport device and the second transport device respectively comprise at least one conveyor belt.
 10. The apparatus according to claim 2, wherein the stack defines a planar front face and the at least one contact element of the retaining device has a planar contact surface acting upon said front face to hold back printed products above the bottom printed product.
 11. The apparatus according to claim 2, wherein the at least one contact element of the retaining device is connected to and driven by a controllable drive.
 12. The apparatus according to claim 2, wherein the stack defines a front face and at least one contact element of the retaining device comprises an endless revolving belt, arranged at the front face of the stack to be separated, for taking hold of at least an area of the front face.
 13. The apparatus according to claim 11, wherein the stack defines a planar front face and the at least one contact element of the retaining device has a planar contact surface acting upon said front face to hold back printed products above the bottom printed product.
 14. The apparatus according to claim 1, wherein the stack defines a planar front face and the at least one contact element of the retaining device comprises an endless revolving belt with a planar contact surface acting upon a portion of said front face, a separating element is arranged between the contact element of the retaining device and the stack of printed products to be separated and can be adjusted with respect to its distance from the passage between the retaining element and the first transport device, and the at least one contact element of the retaining device is connected to and driven by a controllable drive.
 15. An apparatus for sequentially separating individual printed products that are stacked in a height direction between top and bottom printed products, comprising: a first transport device that acts upon the respective sequential bottom printed product along a first feed direction (v) extending perpendicular to the stack height, a second transport device that is arranged upstream of the first transport device and feeds stacks thereto along said first fed direction, a retaining device that holds back printed products above the bottom printed product from transport in the first feed direction and forms a passage with the first transport device for the respective bottom printed product to be separated from the stack as transported along the first feed direction by the first transport device, at least one movable contact element which contacts a surface of the stack with a force acting in a direction (d) toward the first transport device and perpendicular to the first feed direction (v), whereby said force urges the bottom printed product against the first transport device for separation and transport out of the stack while the retaining device holds back products above the bottom printed product.
 16. The apparatus according to claim 15, wherein the stack defines a planar front face, the retaining device includes a retention plate that acts on the front face of the stack to hold back a portion of the printed products above the bottom printed product, and the at least one contact element has a planar contact surface entirely above the first transport device at the front face and to apply a force acting on at least the bottom printed product.
 17. The apparatus according to claim 16, wherein the contact element is adjustable with respect to a distance from the first transport device, and the retention plate is adjustable relative to the contact element with respect to a distance from the first transport device.
 18. The apparatus according to claim 16, wherein the first transport element is a belt that defines a transport plane; the contact element and retaining element are supported together above the first transport element for common displacement in two dimensions parallel to said plane to position the retaining element relative to the front face of the stack as transported by the first transport element.
 19. The apparatus according to claim 18, wherein the contact element is adjustable with respect to a distance from the first transport device, and the retention plate is adjustable relative to the contact element with respect to a distance from the first transport device. 